1. Field of the Invention
The invention relates to a brake actuating system, particularly for heavy duty full power or power assist fluid actuated caliper brakes as used in industrial and marine applications.
2. Prior Art
Heavy duty caliper brakes are commonly fluid actuated by an extensible and retractable brake actuator. The fluid commonly used is air, which is metered by an operator through a compensating regulator valve. Output from the valve is proportional to movement of a manual lever which controls a signal input rod of the valve, the output being metered air from a pressurized fluid source, which output is fed to a spring return actuator or similar device. Because the operator is metering a valve controlling the pressurized fluid, he has no "feel" of his braking signal or braking force, and consequently the brake is sometimes applied too quickly, with a corresponding excessive loading of the system being braked, or too slowly which consequently requires an excessively long time for the device to be braked. In one industrial application, namely draw works as used in oil well drilling wherein a string of drill rods is lowered down a bore hole, accurate "feel" of the braking signal or force is necessary so as to reduce shock loads on the string of drill rods and the braking system. In the past, accidents have occurred resulting from applying brakes too rapidly due to difficulties in feeling the amount of braking force being applied. Also, some prior art brakes cannot be left unattended when engaged because vibration can gradually shift the lever, causing the brake to be disengaged accidentally.